The CAS Registry Mumber 28050-19-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,8,0,5 and 0 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 28050-19: (7*2)+(6*8)+(5*0)+(4*5)+(3*0)+(2*1)+(1*9)=93 93 % 10 = 3 So 28050-19-3 is a valid CAS Registry Number.